Introduction

Children and adults are physiologically different. Even within the pediatric population, there is a wide range of physiological normative values across the age spectrum. This is perhaps most relevant in the neurosurgical setting for the management of intracranial pressure (ICP) and blood pressure. Pathophysiology after traumatic brain injury (TBI) is also different in children. Diffuse brain injury is more common. Focal injury and extra-axial hematomas are less common. There also are differences in the pressure–volume relationships within the skull, metabolic responses to injury, and cerebral hemodynamics—all of which have clinical implications for treatment. Furthermore, the technical aspects of operative management in the pediatric population—with regard to anesthetic control, operative planning, and tissue handling—require special consideration. Although it is beyond the scope of this chapter to cover all the details of every specific emergency operation performed in children, key principles common to the most important of these procedures are addressed.

Indications

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  Insertion of parenchymal monitors (ICP, brain oxygen, microdialysis, etc.). It is the authors’ practice to place (at minimum) an ICP monitor for all patients who require ventilation after TBI and who have an abnormal head computed tomography (CT) scan. Invasive monitoring may also be considered for patients with diffuse injuries, as a normal CT does not preclude a patient from potentially having intracranial hypertension. Intracranial monitoring also may be considered for patients with other acute neurologic pathologies that result in coma and that may be associated with brain swelling and brain ischemia. Open sutures and fontanels in young children should not discourage monitoring, as these patients remain at risk for increased ICP.

  
  
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  Insertion of ventricular drainage catheters. External ventricular drain (EVD) placement enables accurate monitoring of ICP and allows for therapeutic drainage of cerebrospinal fluid (CSF) in the setting of increased ICP. Appropriate indications for EVD placement include a need for ICP monitoring in patients with severe TBI (Glasgow Coma Scale [GCS] ≤ 8) and the presence of hydrocephalus. While there is Class III evidence for use of lumbar drains with a concurrent EVD and open cisterns on CT, it has not been the practice of the authors to use such devices because of concern of herniation.

  
  
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  Operative treatment of depressed skull fractures. Not all closed, depressed fractures require surgery. Minor depressions often will remold over time, especially in the young child. Indications for operative repair include depressed fractures associated with significant mass effect—with or without subadjacent hematoma; compound, depressed fractures; and fractures in cosmetically important areas.

  
  
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  Craniotomy/craniectomy for extra- or intra-axial hematomas. The indications for evacuation of intracranial hematomas conform largely to the corresponding principles in adult trauma. Hematomas associated with significant mass effect are removed. Contusions are most suitable for removal if—in addition to demonstrating mass effect—they are discrete and close to the cortical surface. Hematomas of the temporal lobe and posterior fossa present the greatest risk for significant mass effect.

  
  
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  Decompressive craniectomy. The indications for decompressive craniectomy are similar to those in adults. The expectation of clinical benefit from the procedure, however, may be greater in children than in adults. Craniectomy, if contemplated, should be performed early rather than late—as a second tier therapy in the management of increased ICP refractory to medical treatment.

  
  
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  Cranioplasty. Delayed cranioplasty may be necessary to replace the bone flap after decompressive craniectomy or to address other trauma-related cranial defects.

  
  
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  Repair of growing skull fractures. A growing skull fracture, or leptomeningeal cyst, is a potential complication of skull fractures in young children. Leptomeningeal cysts usually start to develop within a few months of the injury. Pulsation of the brain against an unrecognized dural tear—with interposition of tissue between the edges of the fracture—leads to progressive widening of the fracture and increasing size of the dural defect. The diagnosis becomes clinically evident as a progressively enlarging, pulsatile mass in the region of the previous fracture. Surveillance is warranted for all young children with skull fractures. Clinical follow-up at 2–4 weeks post-injury, with or without further radiographic imaging, is indicated to assess for persistent or increasing swelling in the region of the fracture. If a growing fracture is diagnosed, it requires operative repair.

Preprocedure Considerations

Anesthetic Considerations in Children

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  It is essential that the anesthesiology team have both pediatric and polytrauma experience. Secondary insults contribute substantially to worse outcome and so should be aggressively avoided.

  
  
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  Inadequate management of the respiratory and circulatory systems may lead to secondary insults such as hypoxia and hypotension. Brain swelling may be exacerbated by hypo- or hypertension, hypercarbia, and inadequate pain control.

  
  
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  The endotracheal tube must be fastened securely, particularly if the child’s head is to be turned. Loss of the airway is of greater consequence in children because they deteriorate rapidly. The TBI patient, in particular, has a reduced capacity to tolerate hypoxic insults. Hypocarbia may exacerbate the decreased cerebral blood flow often seen early after TBI, and hypercarbia may increase cerebral blood volume and, consequently, ICP.

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  Induction of anesthesia must be smooth; coughing or bucking may have fatal consequences in patients who already have life-threatening increased ICP.

  
  
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  Often, anesthesiologists are accustomed to maintaining patients at blood pressures in the lower range of normal during elective surgery. This practice may be hazardous when managing the TBI child at risk of early brain ischemia. Also, impairment of pressure autoregulation may result in reduced capacity to accommodate a blood pressure in the lower range of normal. Large bore intravenous access allows adequate response to hemodynamic instability, especially when there may be occult abdominal or thoracic injury.

  
  
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  To estimate what blood pressure is adequate, the anesthesiologist must have access to charts for normal mean arterial pressure ranges for age (and, preferably, height and gender as well).

  
  
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  If a craniotomy or craniectomy is planned, ensure that blood is cross-matched for possible transfusion, especially in the very young. The circulating blood volume of a child is only 70–85 mL/kg depending on age, so relatively small volumes of blood loss in these patients may rapidly lead to hemodynamic instability.

  
  
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  Placement of central venous and arterial lines is recommended for severe TBI patients, not only for adequate intraoperative hemodynamic control, but also to facilitate intensive care unit management thereafter.

  
  
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  If mannitol is required intraoperatively to assist the reduction of brain swelling, the anesthesiologist must ensure that the patient remains euvolemic throughout and that there is an adequate response to the mannitol infusion by monitoring urine output.

  
  
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  Do not use hypotonic or glucose-containing fluids.

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